1. Field of the Invention
The present invention relates to a technology concerning an image capturing apparatus, and particularly relates to a point image restoration process performed on an imaged picture on the basis of a point spread function (PSF).
2. Description of the Related Art
Image deterioration caused by various aberrations of an optical system (e.g., imaging lens) sometimes occurs in an imaged picture obtained by imaging a subject by an image capturing apparatus such as a digital camera.
In order to prevent the image deterioration (diffraction blur, peripheral blur, chromatic aberration of magnification, etc.) caused by the aberration, a technology has been devised in which image data of the subject image is subjected to image processing to eliminate (correct) the image deterioration caused by the aberration.
The image deterioration due to the aberration may be represented by a point spread function (PSF), and an imaged picture deteriorated in an image quality can be subjected to the point image restoration process on the basis of the point spread function to restore the image quality. In other words, the point image restoration process is a process for canceling the image deterioration by subjecting imaged picture data to a restoration filter (inverse filter) of the point spread function.
Since the image deterioration is affected by piece-to-piece variations in the optical system (lens), it is desirable to adjust a parameter for the restoration filter depending on the piece-to-piece variations in the optical system.
Japanese Patent Application Laid-Open No. 2010-086138 (hereinafter referred to as PTL 1) discloses a technology in which measured PSF data obtained from imaging data of a chart for adjustment imaged by each image recording device is used for restoring image data to enable restoration depending on an individual difference (piece-to-piece variations).
Japanese Patent Application Laid-Open No. 2011-124692 (hereinafter referred to as PTL 2) discloses a technology in which an optical image formed so as to be given a predetermined blur through an extended depth of field optical system is captured, and the restoration filter is created from an intensity distribution of a blurred border and an intensity distribution of a targeted border.
Japanese Patent Application Laid-Open No. 2011-193277 (hereinafter referred to as PTL 3) discloses a technology in which even if a lens has a difference in characteristics due to production tolerance, an area having a large square error of a frequency component before and after a restoration process is automatically extracted and displayed in accordance with a restoration item specified by a user such as resolution, and color blur to adjust a parameter for the specified restoration item in response to a user adjustment operation.